Large power type transformers are known to be generators of noise caused by magnetostrictive effects in the core which cause the transformer casing to vibrate. Since transformers are finding more application in residential and industrial areas the transformer noise generated can become a nuisance to persons living and working in the area.
U.S. Pat. No. 3,077,946 discloses a method of suppressing transformer noise by surrounding the transformer tank with an energy absorbing material. It has been discovered that certain regions of the transformer tank produce the the largest percentage of the noise generated by the transformer. It is believed to be more economical and efficient to provide damping facility only to those regions of the transformer tank wall that actually produce sound. U.S. Pat. No. 3,876,034 discloses a sound proofing panel adapted to be applied against a noisy metal surface for attenuating the noise. The soundproof panel comprises a sheet of lead coated with a flexible and elastic material and is applied directly to the noise generating surface. The sound absorption is believed to result by the action of the panel as an inefficient secondary source of sound.
The purpose of this invention is to provide efficient and economic sound reduction to power transformers by the selective application of a sound absorbing device to the regions of the transformer casing which generate the most noise.